Cessna 172N N4737D

Summary

On 17 February 2012 at about 21:52 local time, a Cessna 172N registered N4737D was involved in an accident near Flat Rock, Virginia, United States. One person was on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

17 February 2012 at 21:52

Classification

Accident

Location

Flat Rock, Virginia, United States

Coordinates

37.5203, -77.8203

Aircraft

Cessna 172N

Registration

N4737D

Category

Airplane

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

Manassas → Fayetteville

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

ERA12LA191

Nobody was injured.

The partial loss of engine power due to the failure of the exhaust valve spring seat for reasons that could not be determined.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

According to the pilot, while in cruise flight, the engine began to lose power. He noticed a vibration in the throttle control and an “oily” smell. Engine power decreased to 1,500 rpm. The airplane was unable to maintain altitude, and the pilot elected to make an emergency landing in a field. During the landing roll, the airplane collided with an embankment and sustained substantial damage to the fuselage. An examination of the engine revealed that the No. 4 valve spring seat had broken. A review of the maintenance records revealed that the engine had accumulated 1865.34 hours since the last overhaul 6.5 years before the accident. According to Lycoming Service Instruction 1009AU, the recommended time between overhaul is 2,000 hours or 12 years, whichever occurs first. Further review of the maintenance records revealed compliance with Airworthiness Directive 80-04-03 R2, which covers the replacement of the upper exhaust valve spring seats and the exhaust hydraulic lifters. The exhaust valve seat failed 134.66 hours before the next recommended overhaul. The investigation was unable to determine the reason for the valve seat failure.

Quoted verbatim from the NTSB record.